1. Field of the Invention
This invention relates to motor driven cameras, and more particularly to a control system for co-ordinating a camera and a motor drive unit with a common release actuating button which may be provided in either one of them.
2. Description of the Prior Art
The conventional motor driven camera has two release actuating members one in the camera body and the other in the motor drive unit, while the camera is co-ordinated with the motor drive unit by making use of two switch elements S1 and S2 in the camera body 1, or S1D and S2D in the unit body 2 as shown in FIG. 1. When either one of the actuating members or shutter release buttons is depressed, the first switch element S1 or S1D is closed to start light-metering operation by a circuit 5 in the camera body 1, and is followed by closure of the second switch element S2 or S2D which results in actuation of a camera release. At the completion of an exposure, a motor control circuit 6 is actuated to drive a film winding and shutter cocking mechanism for one cycle of operation. After each cycle of winding operation, the shutter release button is rendered effective to perform the next actuation of the camera release.
Recently, a motor driven camera having a plurality of switched positions for a continuous succession of frame exposures at a high or slow speed and a single frame operation has been developed. In the case of the continuous succession of frame exposures, it is required to start operation of the motor drive unit at the time of actuation of the camera release. For this purpose, the second switch element S2 or S2D is utilized to control actuation of operation of the motor. As the operating voltage for the motor is generally set to 18 volts, being higher than that for the electromagnet controlling the period of actuation of the shutter, for example, 6 volts, it has been the prior art practice to employ a reverse current preventing means or diode 7 as connected between any one of the second switch elements S2 and S2D and the camera control circuit 5, or otherwise the circuit 5 will be damaged by application of the excess voltage thereto, when the second switch element S2 or S2D is opened to cut off the motor drive control circuit 6 from the earth.
The employment of the reverse current prevent diode 7, however, gives rise to disadvantages that, because of a voltage drop (about 0.6 volts) across the diode 7, the satisfactory operating level for the camera must be increased by a corresponding voltage difference to shorten the life-time of a battery in the camera body and to make it more difficult to effect satisfactory performance of the camera as the ambient temperature is decreased, and that, because of the requirement of a high voltage resisting characteristic for the diode 7, it is impossible to fablicate the diode 7 as a part of an integrated circuit with limitation to the design flexibility allowing a camera of reduced size and with increase in the production cost.
It is an object of the present invention to provide a motor driven camera of the type having a plurality of operating modes which has overcome the above mentioned conventional drawbacks.
To achieve this, there is provided an interface circuit between the circuitry of the camera body and that of the motor drive unit to prevent application of an excessive voltage from the motor drive unit to the camera when the second switch element is operated.
Another object of the present invention is to provide a motor driven camera with an electronic device for remote control photography adapted to cooperate with the above described interface circuit.
These and other objects and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which: